A hybrid method for the design of oversampled uniform DFT filter banks
A hybrid method for the design of oversampled uniform DFT filter banks
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DOI：
10.1016/j.sigpro.2005.02.023
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发表时间：
2006-07
期刊：
影响因子：
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通讯作者：
K. Yiu;N. Grbic;S. Nordholm;K. Teo
中科院分区：
文献类型：
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作者：
K. Yiu;N. Grbic;S. Nordholm;K. Teo
为了加快收敛速度和降低计算复杂度，人们提出了子带自适应滤波器。然而，由于混叠效应和幅度失真，子带处理会导致信号恶化。由于在子带中进行进一步的滤波操作，这一问题是不可避免的。本文对混叠效应和幅度失真问题进行了研究。将原型滤波器设计问题描述为一个多准则优化问题，并寻求所有的帕累托最优解。针对该问题的高度非线性和非光滑性，提出了一种新的混合优化方法。使用了不同的原型滤波器，并对它们的性能进行了比较。此外，还研究了子带个数、过采样因子和原型滤波器长度对系统性能的影响。我们发现，通过Kaiser或Dolph-Chebyshev窗口设计的原型滤波器提供了最佳的整体性能。此外，存在一个关键的过采样因子，超过该因子，性能的改善是不合理的。最后，如果原型滤波器的长度随子带数目的增加而增加，则子带级别的增加不会降低性能。
Subband adaptive filters have been proposed to speed up the convergence and to lower the computational complexity of time domain adaptive filters. However, subband processing causes signal degradations due to aliasing effects and amplitude distortions. This problem is unavoidable due to further filtering operations in subbands. In this paper, the problem of aliasing effect and amplitude distortion is studied. The prototype filter design problem is formulated as a multi-criteria optimization problem and all the Pareto optima are sought. Since the problem is highly nonlinear and nonsmooth, a new hybrid optimization method is proposed. Different prototype filters are used and their performances are compared. Moreover, the effect of the number of subbands, the oversampling factors and the length of prototype filter are also studied. We find that prototype filters designed via Kaiser or Dolph–Chebyshev window provide the best overall performance. Also, there is a critical oversampling factor beyond which the improvement in performance is not justified. Finally, if the length of the prototype filter increases with the number of subbands, an increase in the subband level will not deteriorate the performance.